Bacteria could build and power microscopic "wind farms"

Bacterial suspensions develop chaotic active flows that are normally so disorderly that useful power cannot be extracted from them, but a lattice of microscopic rotors changes this(Credit: University of Oxford/Amin Doostmohammadi)

Wind farms are well-established alternative power sources, but they do have their detractors who say they are an eyesore. But a new type of wind farm proposed by researchers at Oxford University is unlikely to attract such criticism. They claim computer simulations have demonstrated it is possible that microscopic wind farms could be built and powered by bacteria to provide a steady, albeit small, source of power.

If you've ever looked at a drop of pond water under a microscope, you've probably seen bacteria and protozoa swimming about at random. At first glance, using these microbes as a power source seems as counterintuitive as herding cats. As bacteria slow spontaneously, the movements of some will counteract the movements of other. The result is that if you were to make a teeny rotor and stick in a petri dish, it would just get buffeted about.

What the Oxford team found was that by replacing a single rotor with a lattice of 64 symmetric microrotors, this active flow of bacteria would spontaneously organize itself. Like a full-size wind farm, the bacteria would organize themselves so that neighboring rotors moved in opposite directions. With this level of self-organization, the farm can produce power.

According to the team, such bacteria-driven wind farms have the potential to one day power microscopic engines for self-assembled and self-powered devices.

"The ability to get even a tiny amount of mechanical work from these biological systems is valuable because they do not need an input power and use internal biochemical processes to move around," says Dr Amin Doostmohammadi of Oxford University's Department of Physics. "At micro scales, our simulations show that the flow generated by biological assemblies is capable of reorganizing itself in such a way as to generate a persistent mechanical power for rotating an array of microrotors."

Bacterial suspensions develop chaotic active flows that are normally so disorderly that useful power cannot be extracted from them, but a lattice of microscopic rotors changes this(Credit: University of Oxford/Amin Doostmohammadi)